Threaded percussion primer



y Feb. 2s, 1967 F. scHAADT ETAL 3,306,203 THREADED PERCUSSION PRIMER Filed March 24, 1964 f /ZW 5- y INVENTGRJ Mig-IM V ATTORNEY:

United States Patent O R 1 Claim. (Cl. 102-45) This application is a continuation-in-part of application Serial No. 104,747 led April 21, 1961, now abandoned.

The invention relates to a threaded percussion primer for cartridges use-d in automatic weapons, there being provided an outwardly open bore, in which the cup-shaped percussion cap is introduced, at the bottom of the threaded percussion primer.

The invention has for its object to provide a munition in which is ensured, :by the simplest possible means, a reliable seal between percussion cap and threaded primer.

According to the invention, this object is achieved in that the bore provided for the cup-shaped percusion primer has a peripheral groovepreferably closed in itselfinto which the adjacent portion of the wall of the cupshaped cap can be driven, with the appropriate deformation taking place, by the impact pressure of the striker. In this way, an absolutely -gas-tight connection between percussion cap and threaded primer is achieved `by very simple means so that the powder gases of the primer char-ge and of the propellant charge, which burn under pressure, cannot discharge rearwardly, i.e. in the direction of the breach mechanism.

Further details of the invention will now be explained with reference to an embodiment thereof which is illustrated in the drawing in which:

FIG. 1 is a longitudinal section on an enlarged scale;

FIG. 2 is a lon-gitudinal section of a portion of the primer on a larger scale and showing the striker pin im mediately upon impact; and

FIG. 3 is similar to FIG. 2 with the parts after the explosion.

As becomes apparent from the drawing, the threaded percussion primer or casing 1 is provided with a threaded portion 2 serving to screw-connect with the cartridge sleeve. The inner end of the threaded primer which points towards the cartridge or the propellant charge has a bore 3 and serves for receiving the primer charge 4. Externally, the primer charge is covered by a disc 5.

On the opposite side of the threaded primer is a second bore 6 which serves for receiving the percussion cap consisting of the cup-shaped element 7, the primer composition 8, and the anvil 9 with ignition apertures 10. The space 11 adjacent the percussion cap is provided with a groove, and preferably an annular groove 13 into which the adjacent wall portion of the cup-shaped primer cap 7, whose front end -bears on the bottom of the bore 6, can be driven by the bearing pressure of the projected striker, while being deformed accordingly. Thus, when the wall thickness of the cup, the shape of the groove, and the bearing pressure of the striker are matched appropriately, the wall of the cup is pushed into the annular groove and establishes a positive connection therewith by virtue of its shape so that, at this point, there is created an additional sealing position in the ymanner of a labyrinth seal.

The drawing clearly shows the cup-shaped element 7 having a rather thick bottom portion and thin side wall with the upper peripheral end 14 abutting against a supporting face 15 which is adjacent the space 11. Thus, when the striker 16 FIGURE 2, impacts forcibly against the thick bottom portion, the thin side wall will be laterally buckled into sealing contact in the annular groove 13 before the pressure of the pow-der gases become effective in the primer.

More specifically,

in order to illustrate precisely what takes place when a shell in accordance with the invention is tired and in this connection, FIG. 2 shows the primer in which the cup-shaped element has a rather thick bottom portion 17 and thin outer walls 18 which, in FIG. 2, is indicated Aby the arrows s. The upper rim or edge 14 of the cup-shaped member abuts against the supporting face 15 in the casing 1 and thus, it abuts against a rigid supporting element. Due to the force of the striker pin 16 striking against the cup-shaped member, the botto-m portion 17 is slightly bulged inwardly as shown in FIG. 2 and as to the thick section D, FIG. 3, and this results in the thin side wall s at 19 being projected slightly into the groove 13 since there is no supporting surface for that portion of the cup-shaped member. Thus, the side walls will bear against the edges x and y of the groove 13 so that there is thus established a tight contact between the cup-shaped member and the primer casing 1. Due to this impact of the striker 16, the cup-shaped member is actually forced inwardly a distance a, FIG. 2. When now the explosion takes place and the accompanying gases are released, there is a further bulging of the walls of the shell into the groove 13 as clearly shown in FIG. 3 and this results in a foreshortening of the walls of the cup-shaped member so that the upper rim 14 will be forced a distance b from the face 15 and away from the supporting face 15. In FIGS. 2 and 3, the distances a and b have been somewhat exaggerated in order to clearly illustrate precisely what takes place since actually, the distances, or rather the shrinkage, of the cup-shaped element is quite small.

What we claim is:

A method of sealing a percussion primer in a casing of a cartridge with a cylindrical bore therein forming a side wall to prevent escape of Ipowder gases during tiring comprising forming an annular groove in the side Wall of the bore, securing a cup-shaped element within the bore containing the primer charge, and laterally forcing a part of the cup-shaped element into the groove by a striker to seal the cup-shaped element in the casing against the escape of powder gases upon the tiring of the cartridge by the impact force of a projected striker.

References Cited by the Examiner UNITED STATES PATENTS 400,165 3/1889 Bayliss 102-45 431,601 7/1890` Lorenz 102-45 472,782 4/ 1892 Bennett 102`45 573,897 12/1896 Mohr IGZ-45 740,790 10/ 1903 Young 102-45 2,381,900 8/1945 Graumann et al 102-45 2,696,191 12/1954 Sheehan 102-865 2,926,607 3/ 1960 Muller et al 102*45 X BENJAMIN A. BORCHELT, Primary Examiner. R. F. STAHL, Assistant Examiner. 

